1. Field of the Invention
The present invention relates generally to a fingerprint reading device, and more particularly to an electrostatic capacity type fingerprint reading device.
2. Related Background Art
Some of systems for authenticating an individual for the purpose of keeping confidentiality, etc. have hitherto used an ID number, a password and so on, however, it was not perfect to maintain the confidentiality because the ID number and the password might leak out. While on the other hand, a system using a fingerprint reading device is proposed as that capable of keeping the confidentiality at a much higher level.
There were hitherto proposed electrostatic capacity type fingerprint reading devices (Japanese Patent Application Laid-Open Publication No.Hei4-231803, etc.) for detecting a fingerprint pattern by utilizing the fact that electrostatic capacities occurred between a group of electrodes arranged in a two-dimensional array and a finger touching on the electrode group through a dielectric substance layer differ corresponding to a ruggedness of the fingerprint. Some of this type of fingerprint reading devices have been utilized.
There was not, however, a well-designed application about what sort of apparatus incorporates such type of fingerprint reading device and how the fingerprint reading device is used, and very few fingerprint reading devices have been utilized.
It is a primary object of the present invention, which was devised under such circumstances, to provide a finger print reading device capable of enhancing a versatility when actually used, increasing productivity and reducing costs.
To accomplish the above object, according to a first aspect of the present invention, a fingerprint reading device comprises an electrostatic capacity type fingerprint reading sensor provided on a liquid crystal panel, and a drive circuit thereof. The fingerprint reading sensor includes detection electrodes arranged in predetermined positions, active elements connected respectively to the detection electrodes, and a protective film provided on the surface thereof.
According to the first aspect of the invention, the fingerprint reading sensor is provided in the vicinity of the liquid crystal panel, whereby the fingerprint reading device is easy to apply to an electronic apparatus, etc. mounted with the liquid crystal panel.
According to a second aspect of the present invention, the fingerprint reading device according to the first aspect of the invention is characterized in that the detection electrodes and the active elements may be arranged in a two-dimensional array.
According to the second aspect of the invention, an image of the fingerprint can be read by the detection electrodes arranged in the two-dimensional array.
According to a third aspect of the present invention, the fingerprint reading device according to the first or second aspect of the invention is characterized in that the liquid crystal panel may have a pair of transparent substrates, one of the transparent substrates may have a protruded portion protruding outside from a display area, and the fingerprint reading sensor may be provided on the protruded portion.
According to the third aspect of the invention, the fingerprint reading sensor can be incorporated integrally with the liquid crystal panel into the electronic apparatus, etc., which saves the installation space.
According to a fourth aspect of the present invention, the fingerprint reading device according to the third aspect of the invention is characterized in that the fingerprint reading sensor may be formed together with the transparent electrodes and the active elements of the liquid crystal panel on one of the transparent substrates by the same process.
According to the fourth aspect of the invention, the fingerprint reading sensor is formed simultaneously in a thin-film process of forming the transparent electrodes and the thin-film active elements of the liquid crystal panel, whereby the manufacturing costs can be decreased to a considerable degree.
According to a fifth aspect of the present invention, in the fingerprint reading device according to the third or fourth aspect, the active element of the fingerprint reading sensor may be a thin-film transistor.
According to the fifth aspect of the invention, the thin-film transistor of the fingerprint reading sensor can be formed by the same process as in the thin-film transistor of the liquid crystal panel.
According to a sixth aspect of the present invention, in the fingerprint reading device according to the first or second aspect, the detection electrode of the fingerprint reading sensor may be a transparent electrode, and the fingerprint reading sensor may be provided in at least a part of the display area of the liquid crystal panel.
According to the sixth aspect of the invention, the fingerprint reading sensor is provided in superposition on the display area of the liquid crystal panel, and it is therefore feasible to incorporate the fingerprint reading sensor together with the liquid crystal panel into the electronic apparatus, etc. and save the installation space of the fingerprint reading sensor.
According to a seventh aspect of the present invention, the fingerprint reading sensor according to the sixth aspect may be provided on the surface of the transparent substrate or a polarizing plate of the liquid crystal panel.
According to the seventh aspect of the invention, the fingerprint reading sensor is provided on the transparent substrate or the polarizing plate and is thereby made integral with the liquid crystal panel.
According to an eighth aspect of the present invention, in the fingerprint reading device according to the sixth or seventh aspect of the invention, the active element of the fingerprint reading sensor may be a thin-film transistor.
According to the eighth aspect of the invention, the fingerprint reading sensor constructed of the transparent electrodes and the thin-film transistors can be easily manufactured by the same manufacturing process as in the liquid crystal panel.